Treatment of leachate from an exploited since 2004 landfill by using two methods of advanced oxidation processes was performed. Fenton’s reagent with two different doses of hydrogen peroxide and iron and UV/H2O2 process was applied. The removal efficiency of biochemically oxidizable organic compounds (BOD5), chemically oxidizable compounds using potassium dichromate (CODCr) and nutrient (nitrogen and phosphorus) was examined. Studies have shown that the greatest degree of organic compounds removal expressed as a BOD5 index and CODCr index were obtained when Fenton’s reagent with greater dose of hydrogen peroxide was used - efficiency was respectively 72.0% and 69.8%. Moreover, in this case there was observed an increase in the value of ratio of BOD5/CODCr in treated leachate in comparison with raw leachate. Application of Fenton’s reagent for leachate treatment also allowed for more effective removal of nutrients in comparison with the UV/H2O2 process.

Lcachates from municipal solid waste landfills should be included in the group of strongly contaminated industrial wastewaters. This results form the presence of highly concentrated various organic and inorganic compounds, which frequently have toxic properties. Therefore, the proper purification of the leachates prior to their discharging to the environment is of great importance. One of the chemical methods that can be used for the purification of leachates is coagulation. The main objective of the experiments presented in the current study was to determine the effect of coagulation, combined with sedimentation, on the physicchemical and toxicological characteristics of leachates from one of a municipal solid waste landfill in Poland. Standard .jar-test" experiments were employed for coagulation. Polyaluminum chloride and ferric chloride were used as coagulants. Raw leachates as well as those after coagulation were tested for toxicity using a battery of tests embracing algal growth inhibition test, microbiotests and IQ Toxicity Tests with crustaceans and bacterial luminescence inhibition test (LUM!Stox). The studies carried out demonstrated that ferric chloride (0.92 g Fc3·/CODc, removed) is more effective technologically in the removal of organic compounds from lcachates than polyaluminum chloride (1.22 g AP'/CODc, removed). For optimal doses of coagulants the most advantageous coagulation effects were achieved at pH 6.5-6.6, adjusted with the use of NaOH. Coagulation conducted under optimal conditions allows for reducing the content of organic compounds, as expressed by CODc, values, from 40 to 84%. This effect of organic compound removal from leachatcs in the process of coagulation did not result in significant decrease of their toxicity, For the above reasons the coagulation process can be useful only as one of the clements· of a technological setup for the purification of leachates from municipal solid waste landfills. The battery of tests used in the studies proved usefulness for the evaluation of the toxicity of leachatcs with varied degree of contamination as well as at various stages of their purification.

These studies examined the concept of concentration and purification of several types of wastewater by freezing and thawing. The experiments demonstrated that freezing of contaminated liquid contributed to concentration of contaminants in solution as well as significant concentration and agglomeration of solid particles. A high degree of purification was achieved for many parameters. The results of comparative laboratory tests for single and multiple freezing are presented. It was found that there was a higher degree of concentration of pollutants in wastewater frozen as man-made snow than in bulk ice. Furthermore, the hypothesis that long storage time of liquid as snow and sufficient temperature gradient metamorphism allows for high efficiency of the concentration process was confirmed. It was reported that the first 30% of the melted liquid volume contained over 90% of all impurities. It gives great opportunities to use this method to concentrate pollutants. The results revealed that the application of this process in full scale is possible. Significant agglomeration of solid particles was also noted. Tests with clay slurry showed that repeated freezing and thawing processes significantly improve the characteristics of slurry for sedimentation and filtration.

The Kalina pond has been well known as a severely degraded area in the Silesia region, Poland. The environmental deterioration results from high contamination of water and bottom sediments with recalcitrant and toxic organic compounds, mainly phenol. The study was aimed at developing a bioremediation-based approach suitable for this type of polluted areas, involving microbiological treatment of water as a key and integral part of other necessary actions: mechanical interventions and the use of physical methods. During the initial biological treatment stage, autochthonous microorganisms were isolated from contaminated samples of water, soil and sediment, then subjected to strong selective pressure by incubation with the pollutants, and finally, cultivated to form a specialised microbial consortium consisting of five extremophilic bacterial strains. Consortium propagation and its biodegradation activity were optimised under variant conditions enabling bacteria to proliferate and to obtain high biomass density at large volumes allowing for the in situ application. After installing aeration systems in the pond, the consortium was surface-sprinkled to launch bioremediation and then both bacterial frequency and the contaminant level was systematically monitored. The complex remediation strategy proved efficient and was implemented on an industrial scale enabling successful remedial of the affected site. Treatment with the specifically targeted and adapted microbial consortium allowed for removal of most organic pollutants within a four-month season of 2022: the chemical oxygen demand (COD) value decreased by 72%, polyaromatic hydrocarbon (PAH) level by 97%, while the content of total phenols and other monoaromatic hydrocarbons (BTEX) dropped below the detection thresholds.

The paper presents results obtained during experiments with constructed wetlands that were built and monitored on the site of a municipal landfill in Southern Poland. The wetland was filled with gravel and rock in which reeds, cattails and willow were planted. A control plot without vegetation was also constructed. Each wetland was loaded with a portion of the leachate generated by the landfill. Measurements of the leachate quality showed very high concentrations of several pollutants. Particularly high concentrations of BOD, COD, nitrogen, and heavy metals were measured. High pollutant levels were probably responsible for the demise of the willows, which were dead within several months of planting. The efficiency of pollution removal with detention time up to 24 h ranged from O to 87% based on decreasing concentration of selected parameters. However, the removal efficiency of the control plot was typically only several percent lower than the removal efficiencies of the plots with vegetation.

Landfilling is the main method of waste disposal in Poland as well as in most countries all over the world. Leachate originating during waste deposition may be a source of ground water pollution. The aim of the paper was to characterize and compare the composition of leachate originating from three landfills in Lublin Province (Poland) and differing in their methods of waste pre-treatment. Ozonation was used in the initial trials to treat landfill leachate. Experiments were carried out to determine whether ozonation using a single dose of 1.8 gO,lm3 has the same effect on the efficiency of organic removal from leachates characterized by different ages and degrees of solid waste pretreatment. From analyses (BOD5, COD, N-NH,, heavy metals) it was concluded, that excluding some fractions (glass, paper, plastics, aluminum, fine organic fraction) from the waste mass affects the leachate quality. The studied oxidizing method was found to influence the BOD5 and COD levels